The present disclosure relates generally to a recombinant human growth and differentiation factor-5 (rhGDF-5) protein and, specifically to expression vector systems for increased production of rhGDF-5, host cells or cell lines for producing rhGDF-5, methods of producing rhGDF-5 using the host cells or cell lines and methods of enhancing production and protein expression of rhGDF-5 protein that are cost-effective, time-saving and manufacturing quality.
Biologic, a therapeutic product, can be made by genetically engineering living cells and requires a high level of precision and care and various factors for its manufacturing process to yield a consistent biologic product each time. For example, a biologic that is produced by recombinant host cells, either in prokaryotes or eukaryotes, can be influenced by (i) individual cell characteristics and (ii) the environment and nutrients provided during the manufacturing process. An example of a biologic is Growth and Differentiation Factor-5 (GDF-5).
GDF-5 belongs to the Bone Morphogenetic Protein (BMP) family, which itself is a subclass of the transforming growth factor-β superfamily of proteins. There are several variants and mutants of GDF-5 (GDF family members), some of which include the first isolated mouse GDF-5 (U.S. Pat. No. 5,801,014); MP52, a human form of GDF-5 (hGDF-5; (WO 95/04819)) or LAP-4 (Triantfilou et al., Nature Immunology 2, 338-345, 2001); cartilage-derived morphogenetic protein (CDMP)-1, an allelic protein variant of hGDF-5 (Chang, S. C. et al., J. Biol. Chem. 269(45):28227-34 (1994); WO 96/14335); rhGDF-5, a recombinant human form prepared from bacteria (EP 0955313); rhGDF-5-Ala83, a monomeric variant of rhGDF-5; BMP-14, a collective term for hGDF-5/CDMP-1 like proteins; SYNS2; Radotermin, the international non-proprietary name designated by the World Health Organization; HMW MP52's, high molecular weight protein variants of MP52; C465A, a monomeric version wherein the cysteine residue responsible for the intermolecular cross-link is substituted with alanine; also other active monomers and single amino acid substitution mutants including N445T, L441 P, R438L, and R438K.
The GDF-5 family members share common structural features including a carboxy terminal active domain and is characterized by a polybasic proteolytic processing site, which can be cleaved to release a mature protein containing seven conserved cysteine residues. The conserved pattern of cysteine residues creates 3 intra-molecular disulfide bonds and one inter-molecular disulfide bond. The active form can be either a disulfide-bonded homodimer of a single family member or a heterodimer of two different members (Massague et al., Ann. Rev. Cell Biol. 6:957 (1990); Sampath et al., J. Biol. Chem. 265:13198 (1990); Celeste et al., Proc. Natl. Acad. Sci. USA 87:9843-7 (1990); U.S. Pat. No. 5,011,691 and U.S. Pat. No. 5,266,683). The proper folding of the GDF-5 protein and formation of these disulfide bonds are essential to biological functioning, and misfolding leads to inactive aggregates and cleaved fragments.
GDF-5 is expressed in the developing central nervous system (O'Keeffe, G. et al., J. Neurocytol. 33(5):479-88 (2004) and has a role in skeletal and joint development (Buxton, P. et al., J. Bone Joint Surg. Am. 83-A, S1(Pt. 1):523-30 (2001); Francis-West, P. et al., Development 126(6):1305-15 (1999); Francis-West, P. et al., Cell Tissue Res. 296(1):111-9 (1999)). The GDF-5 family members are regulators of cell growth and differentiation in both embryonic and adult tissues. For example, GDF-5 may induce angiogenesis in the bone formation process (Yamashita, H. et al., Exp. Cell Res. 235(1):218-226 (1997); CDMP-1 stimulates activity of articular chondrocytes thereby contributing to the integrity of the joint surface (Erlacher, L. et al., Arthritis Rheum. 41(2):263-73 (1998)). Changes in expression patterns of GDF-5 and its receptors are associated with human articular chondrocyte dedifferentiation (Schlegel, W. et al., J. Cell Mol. Med. 13(9B):3398-404 (2009)). As a growth factor, GDF-5 (CDMP) may stimulate proteoglycan production in the human degenerate intervertebral disc (Le Maitre, C. L. et al., Arthritis Res. Ther. 11(5):R137 (2009)). It may increase the survival of neurons that respond to a dopamine neurotransmitter and can be a potential therapeutic molecule associated with Parkinson's disease. (Sullivan and O'Keeffe, J. Anat. 207(3):219-26 (2005)). When rhGDF-5 was delivered on beta-tricalcium phosphate, an effective encouragement of periodontal tissue regeneration in non-human primates was observed. In tissues critical for periodontal repair (e.g. alveolar bone, cementum and periodontal ligament), rhGDF-5 treatment on these tissues showed evidence of regeneration and the response was found to be dose-dependent (Emerton, K. B. et al., J. Dental Res. 90(12):1416-21 (2011). Based on this finding and other similar reports, a biologic such as GDF-5 may offer new approaches or options to regenerate bone during dental implant placement and may save a tooth in patients who are at risk for tooth loss due to periodontal disease.
GDF-5 gene mutations can be associated with the following health conditions, e.g., acromesomelic chrondrodysplasia Grebe type (AMDG; (Thomas, J. T. et al., Nat. Genet. 1:58-64 (1997);), Hunter-Thompson type (AMDH; (Thomas, J. T. et al., Nat. Genet. 3:315-7 (1996)); brachydactyly type C (BDC; Francis-West, P. H. et al., Development, 126(6):1305-15 (1999), Everman, D. B. et al., Am. J. Med. Genet., 112(3):291-6 (2002), Schwabe, G. C. et al., Am. J. Med. Genet. A. 124A(4):356-63 (2004)); DuPan syndrome (DPS), which is also known as fibular hypoplasia and complex brachydactyly (Faiyaz-Ul-Haque, M. et al., Clin. Genet. 61(6):454-8 (2002)); Mohr-Wriedt brachydactyly type A2 (Kjaer, K. W. et al., J. Med. Genet. 43(3):225-31 (2006)); multiple synostoses syndrome type 2 (SYNS2; Dawson, K. et al., Am. J. Human Genet. 78(4):708-12 (2006), Schwaerzer, G. K. et al., J. Bone Miner. Res. 27(2):429-42 (2012)); semidominant brachydactyly A1 (BA1; Byrnes, A. M. et al., Hum. Mutat. 31(10): 1155-62 (2010)); symphalangism (SYM1; Yang, W. et al., J. Hum. Genet. 53(4):368-74 (2008)) or brachydactyly type A2 (BDA2; Seemann, P. et al., J. Clin. Invest. 115(9):2373-81 (2005), Plöger, F. et al., Hum. Mol. Genet. 53(4):368-74 (2008)); susceptibility to osteoarthritis type 5 (OS5; Masuya, H. et al., Hum. Molec. Genet. 16:2366-75 (2007), Miyamoto, Y. et al., Nature Genet. 39:529-53 (2007)); knee osteoarthritis in Thai ethnic population (Tawonsawatruk, T. et al., J. Orthop. Surg. Res. 6:47 (2011)). GDF5 gene variants have been associated with hand, knee osteoarthritis and fracture risk in elderly women, which replicates the previous association between GDF5 variation and height. (Vaes, R. B. et al., Ann Rheum. Dis. 68(11):1754-60 (2009)). All of these associations confirmed that the GDF-5 gene product may play a role in skeletal development.
Expression of GDF-5-related proteins using recombinant DNA techniques has been done and their purification and production for industrial scale have also been explored. See for example, Hötten, U.S. Pat. No. 6,764,994; Makishima, U.S. Pat. No. 7,235,527; Ehringer, U.S. Pat. No. 8,187,837). Both Hötten and Makishima described (1) a complete DNA nucleotide sequence that codes for the TGF-β protein MP-52 and the complete amino acid sequence of MP52; and (2) a composition containing a pharmaceutically active amount of the MP-52 for wound healing and tissue regeneration, treating cartilage and bone diseases and dental implants. According to Makashina, isolation of pure MP-52 at least with the mature region from the mixture was difficult (Makashina, column 1, lines 59-61). To overcome this obstacle, Makashina constructed a DNA plasmid wherein a codon encoding methionine was linked to the DNA sequence that encodes for a 119-amino acid residue protein (MP-52) and wherein the N-terminal alanine of the mature MP-52 protein (120-amino acid residue) was eliminated. Ehringer, on the other hand, described an advanced method for the efficient prokaryotic production and purification of GDF-5 related proteins that resulted in better protein yield, high product purity and improved industrial applicability. Problems encountered during the purification and refolding of the GDF-5-related proteins in large scale were disclosed and addressed.
The use of prokaryotic expression vectors such as bacterial plasmids for expressing preventive or therapeutic peptides (biologics) is very critical and beneficial not only for biochemical research and biotechnology but even more so for medical therapy. Such use is the basis of many biologics manufacturing processes. High-cell density (HCD) fermentation methods that employ these processes offer many advantages over traditional methods in that the final product concentrations are higher, downtime and water usage are reduced, and overall productivity is improved resulting in lower set-up and operating costs.
The recombinant protein and plasmid DNA production typically involves: (1) bacterial propagation and fermentation production, wherein a plasmid encoding a gene of interest is transformed into a bacterial cell, typically Escherichia coli (E. coli), propagated to make master and working cell banks, and further grown in a bioreactor (e.g., fermentor) to make production cells that contain high yields of the plasmid; and (2) purification and formulation stability, wherein the production cells are lysed and plasmid DNA carrying the gene of interest is purified by a plurality of purification methods and formulated for delivery. Expression is particularly higher if the gene of interest is codon optimized to match that of the target organism, which leads to improved gene function and increased protein expression, which ultimately leads to cost-effectiveness of mass producing the recombinant protein.
Plasmid fermentation processes for plasmid production should be optimized to retain a high percentage of supercoiled plasmid. Other plasmid forms are difficult to eliminate during purification and their presence are undesirable. Fermentation media and processes needs to be optimized for plasmid yield, plasmid quality and compatibility of the resultant cells for harvest and lysis. There are about three fermentation processes that can be utilized to initiate production, namely: batch, batch-fed or continuous fermentation processes. For a large scale production, a batch fermentation that generally yields about 10-20 mg/L of plasmid DNA has its limitations such as uncontrolled growth rates and waste product accumulation (e.g., production of reduced carbon metabolites such as acetates, lactates and formates) that ultimately would lead to inhibition of bacterial growth. To prevent these issues from occurring and to increase plasmid yield, fed-batch or continuous high cell density fermentation can be a better option. Continuous fermentation processes are more conducive to the production of large amounts of a single product but sterility remains an issue. Fed-batch fermentation begins with a short batch fermentation and is proceeded by the addition of media at a defined rate. It is more flexible and consistent than the batch method and allows for simple optimization of fermentation profiles for each plasmid DNA product. When employing a defined growth rate strategy as a form of feed strategy, a feed media is added at rates that are determined based on a pre-established growth profile, wherein the feed is triggered by an initial DO2 spike (caused by the exhaustion of initial bolus of glucose in the media). Peterson, M. and Brune, M., in BioPharm International Supplements entitled: “Maximizing Yields of Plasmid DNA Processes,” Jun. 2, 2008.
Chemically-defined (minimal) media contain known quantities of ingredients added to purified water. The absence of animal-derived components in chemically-defined media may be more desirable from a regulatory standpoint due to concerns over BSE/TSE (spongiform encephalopathy/transmissible spongiform encephalopathy). They have reproducibility (their components have known chemical structures that can allow consistent performance of cells in the medium), greater simplicity of both downstream processing and the analysis of product and greater control of feeding strategy when carbon sources are known.
Complex media, on the other hand, are digests of food and agriculture by-products (i.e. protein hydrolysate and yeast extract). They can provide a majority of needed nutrients to host cell (e.g., Escherichia coli) fermentation. They may produce high yields at lower costs (thus, more cost-effective) and less control over individual components and possibly vary from lot-to-lot.
Semi-defined media contain small concentrations of complex ingredients usually from about 0.05 to about 0.5% added to a chemically defined media. Semi-defined media can maximize performance while minimizing downstream processing issues. Small amount of complex material may provide enough nutrients to enhance growth of microorganisms without interfering with recovery or analysis.
Given the role of GDF-5 in cell growth and differentiation, in particular, skeletal and joint development and bone regeneration, there is a critical need for a therapeutic rhGDF-5 biologic that can be manufactured in large scale processes. There is an urgent need for improving the manufacturing process of rhGDF-5 that can be cost-effective, time-saving and manufacturing quality.